In 1893, his granduncle, Ernest II, Duke of Saxe-Coburg and Gotha, the elder brother of his paternal grandfather, died without legitimate heirs. Being ineligible under Saxe-Coburg-Gotha house law to succeed to the duchy due to his status as the heir apparent to an existing throne,[2] the Prince of Wales had previously renounced his claim to the ducal throne. Thus, the succession devolved to Alfred's father, who was at that time the Duke of Edinburgh. Alfred thus became the Hereditary Prince of Saxe-Coburg and Gotha.

Prince Alfred had lived in Clarence House in the early years of his life with his parents and sisters; after his father's accession to the ducal throne of Saxe-Coburg and Gotha, he moved to Schloss Rosenau, near Coburg.

Group photograph of Hereditary Prince Alfred of Saxe-Coburg and Gotha celebrating his majority.

The exact circumstances of Alfred's death are not known, and varying accounts have been published. His sister Marie's memoirs simply say his health "broke down", and other writers have said that he had "consumption".[3]:62The Times published an account stating he had died of a tumor,[3]:62 while the Complete Peerage gives the generally accepted account that he "shot himself".[4] Various authors have speculated on reasons why he might have killed himself, and one author, Frank Bush, claimed to have been a descendant of a secret marriage between Alfred and Mabel Fitzgerald, granddaughter of the 4th Duke of Leinster, and claimed that friction between Alfred and his family over the "secret marriage" was the cause of the suicide.[3]:176, fn. 2[a] Despite the lack of documentary evidence, and the lack of contemporary reference, other authors have repeated Bush's assertion that Alfred and Mabel married, including John van der Kiste and Bee Jordaan in Dearest Affie, and the assertion is repeated as fact in the official family history (Das Haus von Sachsen-Coburg und Gotha).[2]

As a male-line grandson of the British Sovereign, young Alfred bore the royal arms, with an inescutcheon of the shield of Saxony, all differenced by a label argent of five points, the odd bearing crosses gules and even anchors azure.[9]

^Unfortunately for this theory, which was first published in the 1940s, and for Bush's claimed ancestry, there is no evidence Alfred and Mabel ever met; at the time of their alleged civil and religious marriages in 1898 (of which no records exist) Mabel was under 14 years old, and when Mabel contracted a documented marriage to William Clarke Hadoke in 1910 she is described as a spinster rather than a widow.[3]:176, fn. 2